Three new xanthones, oblongixanthone F-H (1-3), along with eight known xanthones (4-11), were isolated from an EtOAc extract of the twigs of Garcinia oblongifolia. Their structures were elucidated by spectroscopic analysis including 1D- and 2D-NMR spectroscopy and mass spectrometry. The antidiabetic effects of all isolated compounds were evaluated by in vitro α-glucosidase and PTP1B inhibition assays. Compound 11 was the most active compound, and inhibited α-glucosidase and PTP1B with IC50 values of 1.7±0.5 and 14.1±3.5μM, respectively.
Keywords: Acarbose (PubChem CID: 444254); Cowagarcinone E (PubChem CID: 11421303); Cowanin (PubChem CID: 11754819); Cowanol (PubChem CID: 101671063); Garcinia oblongifolia; Norcowanin (PubChem CID: 11518330); Oblongixanthone C (PubChem CID: 25209204); PTP1B; RK682 (PubChem CID: 54678922); Rubraxanthone (PubChem CID: 9953366); Type 2 diabetes; Xanthones; α-Glucosidase.
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